Refineries and chemical plants often discharge combustible waste gas to a flare. The flare can produce undesirable emissions in form of particulate smoke and smokeless release of the waste gas that remains unburned from inefficient combustion. Both types of the emissions present environmental pollution issues.
The combustion efficiency of the flare fails to provide a direct correlation to whether or not the flare produces smoke. Even with almost complete combustion, the flare may produce unacceptable levels of the smoke. The flare may however not generate any smoke while operating at unacceptable low levels for the combustion efficiency.
Injecting steam at combustion of the waste gas facilitates with suppressing generation of the smoke. Prior systems utilize various techniques that attempt to determine amount of the steam needed to ensure suppression of the smoke. Given lack of correlation between the combustion efficiency and smoking, problems can arise with these techniques resulting in the flare still emitting either the smoke or smokeless release of the waste gas that remains unburned. The flare for example may produce the smoke despite a false smokeless determination based only on the combustion efficiency as may be determined by infrared radiation measurements. In addition, introducing more of the steam to the flare may further reduce the combustion efficiency when assuming that the combustion efficiency being below a certain point implies tendency for the flare to produce the smoke.
Therefore, a need exists for improved methods and systems for monitoring and controlling a flare.